Facebook originally started testing a new free (minus and data usage fees you incur from your carrier) calling feature for users of its Facebook Messenger app for iPhone in Canada early this year, and now the service is available to U.S. users as well. The free call button app now shows up in the app for U.S. users, in any conversation where both parties are using the Facebook Messenger app.

This is a pretty handy feature for users of the social network, especially since unlike with Skype, Viber or other VoIP calling apps, you already likely have a wide network of contacts you’d actually want to have live voice conversations with built-in and ready to go on Facebook. And while it isn’t entirely free on cellular connections, since it uses your data connection, it is completely free at home on Wi-Fi, which means it can likely replace a home phone for a lot of users if they’re still hanging on to one, or at least for-pay at-home VoIP services.